Protection of Neonatal Broiler Chickens Following in ovo Delivery of Oligodeoxynucleotides Containing CpG Motifs (CpG-ODN) Formulated with Carbon Nanotubes or Liposomes

Advances in Poultry Vaccines: Leveraging Biotechnology for Improving Vaccine Development, Stability, and Delivery

With the rapidly increasing demand for poultry products and the current challenges facing the poultry industry, the application of biotechnology to enhance poultry production has gained growing significance. Biotechnology encompasses all forms of technology that can be harnessed to improve poultry health and production efficiency. Notably, biotechnology-based approaches have fueled rapid advances in biological research, including (a) genetic manipulation in poultry breeding to improve the growth and egg production traits and disease resistance, (b) rapid identification of infectious agents using DNA-based approaches, (c) inclusion of natural and synthetic feed additives to poultry diets to enhance their nutritional value and maximize feed utilization by birds, and (d) production of biological products such as vaccines and various types of immunostimulants to increase the defensive activity of the immune system against pathogenic infection. Indeed, managing both existing and newly emerging infectious diseases presents a challenge for poultry production. However, recent strides in vaccine technology are demonstrating significant promise for disease prevention and control. This review focuses on the evolving applications of biotechnology aimed at enhancing vaccine immunogenicity, efficacy, stability, and delivery.

Preventing bacterial disease in poultry in the post-antibiotic era: a case for innate immunity modulation as an alternative to antibiotic use

The widespread use of antibiotics in the poultry industry has led to the emergence of antibiotic-resistant bacteria, which pose a significant health risk to humans and animals. These public health concerns, which have led to legislation limiting antibiotic use in animals, drive the need to find alternative strategies for controlling and treating bacterial infections. Modulation of the avian innate immune system using immunostimulatory compounds provides a promising solution to enhance poultry immune responses to a broad range of bacterial infections without the risk of generating antibiotic resistance. An array of immunomodulatory compounds have been investigated for their impact on poultry performance and immune responses. However, further research is required to identify compounds capable of controlling bacterial infections without detrimentally affecting bird performance. It is also crucial to determine the safety and effectiveness of these compounds in conjunction with poultry vaccines. This review provides an overview of the various immune modulators known to enhance innate immunity against avian bacterial pathogens in chickens, and describes the mechanisms involved.

Enhancement of protective efficacy of innate immunostimulant based formulations against yolk sac infection in young chicks

This study was conducted to characterize and compare the protective effects of various innate immune stimulants against yolk sac infection (YSI) caused by an avian pathogenic Escherichia coli in young chicks. The immune stimulants were administered alone or in various combinations of unmethylated CpG oligodeoxynucleotides (CpG), polyinosinic:polycytidylic acid (Poly I:C), and avian antimicrobial peptides (AMPs). Routes included in ovo or in ovo followed by a subcutaneous (S/C) injection. CpG alone and in combination with Poly I:C, truncated avian cathelicidin (CATH)-1(6-26), avian beta defensin (AvBD)1, and CATH-1(6-26) + AvBD1, were administered in ovo to 18-day-old embryonated eggs for gene expression and challenge studies. Next, CpG alone and the potentially effective formulation of CpG + Poly I:C, were administrated via the in ovo route using 40 embryonated eggs. At 1 day post-hatch, half of each group also received their respective treatments via the S/C route. Four hours later, all chicks were challenged using E. coli strain EC317 and mortalities were recorded for 14 d. The first challenge study revealed that amongst the single use and combinations of CpG with different innate immune stimulants, a higher protection and a lower clinical score were offered by the combination of CpG + Poly I:C. The second challenge study showed that this combination (CpG + Poly I:C) provides an even higher level of protection when a second dose is administered via the S/C route at 1 day post-hatch. The current research highlights the efficacy of a combination of CpG + Poly I:C administered either in ovo or in ovo along with a S/C injection and its potential use as an alternative to antibiotics against yolk sac infection in young chicks.

Comparison of Therapeutic Antibiotics, Probiotics, and Synthetic CpG-ODNs for Protective Efficacy Against Escherichia coli Lethal Infection and Impact on the Immune System in Neonatal Broiler Chickens

The poultry industry needs alternatives to antibiotics, as there are growing public concerns about the emergence of antimicrobial resistance owing to antimicrobial use in animal production. We have reported that the administration of neonatal chicks with synthetic DNA oligodeoxynucleotides containing unmethylated cytosine guanine dinucleotide (CpG) motifs (CpG-ODN) can protect against bacterial pathogens in chickens. The objective of this study was to compare the immunoprotective effects of CpG-ODN and probiotics against Escherichia coli infection vs. commonly used therapeutic antibiotics. Day-old broiler chicks were divided into five groups (n = 35/group; 30 for the challenge experiment and 5 for the flow cytometry analysis). The chicks in Group 1 received a single dose of CpG-ODN by the intramuscular route on day 4 (D4) posthatch (PH), and Group 2 received drinking water (DW) with a probiotic product (D1-D15 PH, DW). The Group 3 chicks received tetracycline antibiotics during D9-D13 in DW; the Group 4 chicks got sodium sulfamethazine on D9, D10, and D15 PH in DW; and the Group 5 chicks were administered intramuscular (IM) saline D4 PH, DW. We challenged all the groups (n = 30/group) with E. coli (1 × 10⁵ or 1 × 10⁶ colony-forming units/bird) on D8 PH through the subcutaneous route. Our data demonstrated that the CpG-ODNs, but not the probiotics, could protect neonatal broiler chickens against lethal E. coli septicemia, as would the tetracycline or sodium sulfamethazine. The flow cytometry analysis (n = 5/group) revealed enrichment of immune cells in the CpG-ODN group and a marked decrease in macrophages and T-cell numbers in antibiotics-treated groups, indicating immunosuppressive effects. Our data showed that, like therapeutic antibiotics, CpG-ODNs reduced clinical signs, decreased bacterial loads, and induced protection in chicks against E. coli septicemia. Unlike therapeutic antibiotics-induced immunosuppressive effects, CpG-ODN caused immune enrichment by increasing chicken immune cells recruitment. Furthermore, this study highlights that, although therapeutic antibiotics can treat bacterial infections, the ensuing immunosuppressive effects may negatively impact the overall chicken health.

Exposure of embryonating eggs to Enterococcus faecalis and Escherichia coli potentiates E. coli pathogenicity and increases mortality of neonatal chickens

Enterococci and Escherichia coli are opportunistic pathogens of poultry and are associated with embryo and neonatal chick mortality. We have recently demonstrated that 56% of dead broiler chicken embryos in commercial hatcheries in western Canada were due to the coinfection of Enterococcus species and E. coli. The objective of this study was to investigate the host-pathogen interactions of Enterococcus faecalis and E. coli in developing chicken embryos. Embryonating eggs at 12 d of incubation were dipped in a solution of E. faecalis and/or E. coli for 30 s to expose the eggshell to study the migration and colonization of E. faecalis and E. coli in the internal organs of chicken embryos and subsequent neonatal chicken mortality following hatch. A multidrug-resistant E. faecalis isolate from a dead chicken embryo and an E. faecalis isolate from a case of yolk sac infection were able to colonize the internal organs of chicken embryos rapidly compared to an E. faecalis isolate from a healthy chicken without affecting viability or hatchability of embryos. Although E. faecalis colonized internal organs of chicken embryos, no evidence of inflammation of these organs nor the expression of virulence genes of E. faecalis was observed. Although E. faecalis and E. coli alone did not affect the viability of embryos, a significantly high neonatal chicken mortality (27%) was observed following exposure of embryos to both E. faecalis and E. coli. Upregulation of IL-1 and CXCR4 was evident 48 h before peak mortality of neonatal chickens; this could suggest a possible link of cytokine dysregulation to increased mortality in coinfected neonatal chickens. However, further studies are warranted to investigate this issue vis-à-vis coinfection with E. faecalis and E. coli in chicken embryos and neonatal chickens.

In ovo Feeding as a Tool for Improving Performance and Gut Health of Poultry: A Review

Early growth and development of the gastrointestinal tract are of critical importance to enhance nutrients' utilization and optimize the growth of poultry. In the current production system, chicks do not have access to feed for about 48-72 h during transportation between hatchery and production farms. This lag time affects early nutrient intake, natural exposure to the microbiome, and the initiation of beneficial stimulation of the immune system of chicks. In ovo feeding can provide early nutrients and additives to embryos, stimulate gut microflora, and mitigate the adverse effects of starvation during pre-and post-hatch periods. Depending on the interests, the compounds are delivered to the embryo either around day 12 or 17 to 18 of incubation and via air sac or amnion. In ovo applications of bioactive compounds like vaccines, nutrients, antibiotics, prebiotics, probiotics, synbiotics, creatine, follistatin, L-carnitine, CpG oligodeoxynucleotide, growth hormone, polyclonal antimyostatin antibody, peptide YY, and insulin-like growth factor-1 have been studied. These compounds affect hatchability, body weight at hatch, physiological functions, immune responses, gut morphology, gut microbiome, production performance, and overall health of birds. However, the route, dose, method, and time of in ovo injection and host factors can cause variation, and thereby inconsistencies in results. Studies using this method have manifested the benefits of injection of different single bioactive compounds. But for excelling in poultry production, researchers should precisely know the proper route and time of injection, optimum dose, and effective combination of different compounds. This review paper will provide an insight into current practices and available findings related to in ovo feeding on performance and health parameters of poultry, along with challenges and future perspectives of this technique.

CpG-ODN induced antimicrobial immunity in neonatal chicks involves a substantial shift in serum metabolic profiles

Synthetic CpG-ODNs can promote antimicrobial immunity in neonatal chicks by enriching immune compartments and activating immune cells. Activated immune cells undergo profound metabolic changes to meet cellular biosynthesis and energy demands and facilitate the signaling processes. We hypothesize that CpG-ODNs induced immune activation can change the host’s metabolic demands in neonatal chicks. Here, we used NMR-based metabolomics to explore the potential of immuno-metabolic interactions in the orchestration of CpG-ODN-induced antimicrobial immunity. We administered CpG-ODNs to day-old broiler chicks via intrapulmonary (IPL) and intramuscular (IM) routes. A negative control group was administered IPL distilled water (DW). In each group (n = 60), chicks (n = 40) were challenged with a lethal dose of Escherichia coli, two days post-CpG-ODN administration. CpG-ODN administered chicks had significantly higher survival (P < 0.05), significantly lower cumulative clinical scores (P < 0.05), and lower bacterial loads (P < 0.05) compared to the DW control group. In parallel experiments, we compared NMR-based serum metabolomic profiles in neonatal chicks (n = 20/group, 24 h post-treatment) treated with IM versus IPL CpG-ODNs or distilled water (DW) control. Serum metabolomics revealed that IM administration of CpG-ODN resulted in a highly significant and consistent decrease in amino acids, purines, betaine, choline, acetate, and a slight decrease in glucose. IPL CpG-ODN treatment resulted in a similar decrease in purines and choline but less extensive decrease in amino acids, a stronger decrease in acetate, and a considerable increase in 2-hydroxybutyrate, 3-hydroxybutyrate, formic acid and a mild increase in TCA cycle intermediates (all P < 0.05 after FDR adjustment). These perturbations in pathways associated with energy production, amino acid metabolism and nucleotide synthesis, most probably reflect increased uptake of nutrients to the cells, to support cell proliferation triggered by the innate immune response. Our study revealed for the first time that CpG-ODNs change the metabolomic landscape to establish antimicrobial immunity in neonatal chicks. The metabolites highlighted in the present study can help future targeted studies to better understand immunometabolic interactions and pinpoint the key molecules or pathways contributing to immunity.

Aerosol delivery of synthetic DNA containing CpG motifs in broiler chicks at hatch under field conditions using a commercial-scale prototype nebulizer provided protection against lethal Escherichia coli septicemia

Synthetic DNA containing CpG motifs (CpG-ODN) are potent innate immune stimulators in neonatal and adult broiler chickens against bacterial septicemia. We have recently demonstrated that intrapulmonary (IPL) delivery of CpG-ODN as microdroplets under laboratory conditions can protect neonatal chickens against lethal Escherichia coli septicemia. The objectives of this study were to develop a commercial-scale poultry nebulizer (CSPN) that can deliver CpG-ODN as microdroplets in neonatal broiler chicks in the hatcheries and study the efficacy of CSPN in inducing immune-protective effects under different environmental conditions in 2 geographical locations in Canada. Three field experiments were conducted in commercial poultry hatcheries during different seasons of the year in Saskatchewan and British Columbia, Canada. Neonatal broiler chicks (n = 8,000/experiment) received CpG-ODN by the IPL route in the CSPN chamber for 30 min, and control chicks received distilled water (DW) for 30 min. Broiler chicks (CpG-ODN—240 chicks/experiment and DW—40 chicks/experiment) were randomly sampled from all locations of the CSPN after nebulization and challenged with a lethal dose of E. coli to examine the CpG-ODN nebulization induced protection. We found a significant level (P < 0.05) of protection in broiler chicks against E. coli challenge, suggesting that the newly built CSPN successfully delivered CpG-ODN via the IPL route. We found that when the CSPN was maintained at humidex 28°C or below and relative humidity (RH) between 40 and 60%, neonatal birds were significantly (P < 0.05) protected against E. coli septicemia after IPL delivery of CpG-ODN. By contrast, protection in chicks was adversely affected when the CSPN was maintained at the humidex of 29°C or higher and RH of 70%. Overall, the present study successfully built a CSPN for CpG-ODN delivery in chicks at the hatchery and revealed that the temperature, humidity, and humidex were critical parameters in CSPN for efficient delivery of CpG-ODN.

An integrated transcriptomics and metabolomics study of the immune response of newly hatched chicks to the cytosine-phosphate-guanine oligonucleotide stimulation

The immunological immaturity of the innate immune system during the first-week post-hatch enables pathogens to infect chickens, leading to the death of the animals. Current preventive solutions to improve the resistance of chicks to infections include vaccination, breeding, and sanitation. Other prophylactic solutions have been investigated, such as the stimulation of animal health with immunostimulants. Recent studies showed that administration of immune-modulators to one-day-old chicks, or in ovo, significantly reduces mortality in experimental bacterial or viral infection challenge models. Owing to a lack of molecular biomarkers required to evaluate chicken immune responses and assess the efficacy of vaccines or immune-modulators, challenge models are still used. One way to reduce challenge experiments is to define molecular signatures through omics approaches, resulting in new methodologies to rapidly screen candidate molecules or vaccines. This study aims at identifying a dual transcriptomics and metabolomics blood signature after administration of CpG-ODN (cytosine-phosphate-guanine oligodeoxynucleotides), a reference immune-stimulatory molecule. A clinical study was conducted with chicks and transcriptomics and metabolomics analyses were performed on whole-blood and plasma samples, respectively. Differentially expressed genes and metabolites with different abundance were identified in chicks treated with CpG-ODN. The results showed that CpG-ODN activated the innate immune system, within hours after administration, and its effect lasted over time, as metabolomics and transcriptomics profiles still varied 6 D after administration. In conclusion, through an integrated clinical omics approach, we deciphered in part the mode of action of CpG-ODN in post-hatch chicks.

Mucosal delivery of CpG-ODN mimicking bacterial DNA via the intrapulmonary route induces systemic antimicrobial immune responses in neonatal chicks

The transition to antibiotic-free poultry production in the face of pathogenic threats is a very challenging task. We recently demonstrated that mucosal delivery of CpG-ODN alone by the intrapulmonary route (IPL) has potential as an effective alternative to antibiotics in neonatal chicks against Escherichia coli septicemia. How exactly mucosal delivery of CpG-ODN elicits, protective antibacterial immunity remained poorly understood. In this study, CpG-ODN or saline was delivered via the intrapulmonary route to day-old chicks (n = 80/group) using a compressor nebulizer in an acrylic chamber (1 mg/mL CpG-ODN for 15 minutes). In the first part of the study, two days after mucosal CpG-ODN delivery, 40 chicks from each group were challenged subcutaneously with 1 × 10⁵ cfu (n = 20) or 1 × 10⁶ cfu (n = 20) of E. coli and the mortality pattern was monitored for seven days. We found significantly higher survival, better clinical conditions and lower bacterial loads in chicks that received mucosal CpG-ODN. To explore the mechanisms behind this protective immunity, we first looked at the kinetics of the cytokine gene expression (three birds/ group/ time for 10 time-points) in the lungs and spleens. Multiplex gene analysis demonstrated a significant elevation of pro-inflammatory cytokine genes mRNA in the CpG-ODN group. Interleukin (IL)-1β robustly upregulated many folds in the lung after CpG-ODN delivery. Lipopolysaccharide-induced tumor necrosis factor (LITAF) and IL-18 showed expression for an extended period in the lungs. Anti-inflammatory cytokine IL-10 was upregulated in both lungs and spleen, whereas IL-4 showed upregulation in the lungs. To investigate the kinetics of immune enrichment in the lungs and spleens, we performed flow cytometry, histology, and immunohistochemistry at 24, 48 and 72 hrs after CpG-ODN delivery. CpG-ODN treated lungs showed a significant enrichment with monocytes/macrophages and CD4⁺ and CD8⁺ T-cell subsets. Macrophages in CpG-ODN treated group demonstrated mature phenotypes (higher CD40 and MHCII expression). Importantly, mucosal delivery of CpG-ODN via the intrapulmonary route significantly enriched immune compartment in the spleen as well, suggesting a systemic effect in neonatal chicks. Altogether, intrapulmonary delivery of aerosolized CpG-ODN orchestrates protective immunity against E. coli septicemia by not only enhancing mucosal immunity but also the systemic immune responses.

Avian Pattern Recognition Receptor Sensing and Signaling

Pattern recognition receptors (PRRs) are a class of immune sensors that play a critical role in detecting and responding to several conserved patterns of microorganisms. As such, they play a major role in the maintenance of immune homeostasis and anti-microbial defense. Fundamental knowledge pertaining to the discovery of PRR functions and their ligands continue to advance the understanding of immune system and disease resistance, which led to the rational design and/or application of various PRR ligands as vaccine adjuvants. In addition, the conserved nature of many PRRs throughout the animal kingdom has enabled the utilization of the comparative genomics approach in PRR identification and the study of evolution, structural features, and functions in many animal species including avian. In the present review, we focused on PRR sensing and signaling functions in the avian species, domestic chicken, mallard, and domestic goose. In addition to summarizing recent advances in the understanding of avian PRR functions, the present review utilized a comparative biology approach to identify additional PRRs, whose functions have been well studied in mammalians but await functional characterization in avian.

CpG-ODN Induces a Dose-Dependent Enrichment of Immunological Niches in the Spleen and Lungs of Neonatal Chicks That Correlates with the Protective Immunity against Escherichia coli

Immunoprotective function of oligodeoxynucleotides containing CpG motifs (CpG-ODN) has been demonstrated in neonatal chickens against common bacterial pathogens such as E.coli and Salmonella sp. Our recent study reported that CpG-ODN administration enriches immune compartments in neonatal chicks. However, a causal relationship between CpG-ODN-induced immune enrichment and protective mechanisms remains unestablished. In this study, we investigated in ovo administered CpG-ODN-mediated immune cell recruitment in the immunological niches in lymphoid (spleen) and nonlymphoid (lungs) organs using various doses of CpG-ODN and examined whether the immunological profiles have any correlation with immunoprotection against E.coli infection. Eighteen-day-old embryonated eggs were injected with either 5, 10, 25, and 50 μg of CpG-ODN or saline (n = ~40 per group). On the day of hatch (72 hr after CpG-ODN treatment), we collected the spleen and lungs (n = 3‐4 per group) and examined the recruitment of macrophages/monocytes, their expression of MHCII and CD40, and the number of CD4⁺ and CD8⁺ T-cell subsets in the immunological niches in the spleen and lungs using flow cytometry. We observed the dose-dependent recruitment of immune cells, wherein 25 μg and 50 μg of CpG-ODN induced significant enrichment of immunological niches in both the spleen and the lungs. Four days after the CpG-ODN treatment (1-day after hatch), chicks were challenged with a virulent strain of E. coli (1 × 10⁴ or 1 × 10⁵ cfu, subcutaneously). Clinical outcome and mortality were monitored for 8 days postchallenge. We found that both 25 μg and 50 μg of CpG-ODN provided significant protection and reduced clinical scores compared to saline controls against E. coli infection. Overall, the present study revealed that CpG-ODNs orchestrate immunological niches in neonatal chickens in a dose-dependent manner that resulted in differential protection against E. coli infection, thus supporting a cause and effect relationship between CpG-ODN-induced immune enrichment and the antibacterial immunity.

Development of innate immunity in chicken embryos and newly hatched chicks: a disease control perspective

Newly hatched chickens are confronted by a wide array of pathogenic microbes because their adaptive immune defences have limited capabilities to control these pathogens. In such circumstances, and within this age group, innate responses provide a degree of protection. Moreover, as the adaptive immune system is relatively naïve to foreign antigens, synergy with innate defences is critical. This review presents knowledge on the ontogeny of innate immunity in chickens pre-hatch and early post-hatch and provides insights into possible interventions to modulate innate responses early in the life of the bird. As in other vertebrate species, the chicken innate immune system which include cellular mediators, cytokine and chemokine repertoires and molecules involved in antigen detection, develop early in life. Comparison of innate immune systems in newly hatched chickens and mature birds has revealed differences in magnitude and quality, but responses in younger chickens can be boosted using innate immune system modulators. Functional expression of pattern recognition receptors and several defence molecules by innate immune system cells of embryos and newly hatched chicks suggests that innate responses can be modulated at this stage of development to combat pathogens. Improved understanding of innate immune system ontogeny and functionality in chickens is critical for the implementation of sound and safe interventions to provide long-term protection against pathogens. Next-generation tools for studying genetic and epigenetic regulation of genes, functional metagenomics and gene knockouts can be used in the future to explore and dissect the contributions of signalling pathways of innate immunity and to devise more efficacious disease control strategies.

Intrapulmonary Delivery of CpG-ODN Microdroplets Provides Protection Against Escherichia coli Septicemia in Neonatal Broiler Chickens

Synthetic oligodeoxynucleotides (ODN) containing unmethylated cytosine phosphodiester guanine (CpG) motifs (CpG-ODN) are effective immunostimulatory agents against a variety of viral, bacterial, and protozoan diseases in different animals including poultry. We have recently demonstrated that in ovo injection of CpG-ODN confers protection in neonatal chickens against bacterial septicemias. The objective of this study was to investigate the effectiveness of needle-free intrapulmonary (IPL) delivery of CpG-ODN microdroplets against Escherichia coli infection in neonatal chicks. In the present study, we used 880 chicks in total keeping 40 chicks per group. Chicks were delivered CpG-ODN or saline by IPL at the day 1 of hatch. Three days later, chicks were challenged with two doses (1 × 10⁴ CFU, n = 20 or 1 × 10⁵ CFU, n = 20) of E. coli. Chicks treated with CpG-ODN by the IPL route had significantly lower clinical signs and bacterial load compared to the group treated with saline ( P < 0.05). CpG-ODN-treated groups were significantly protected against E. coli septicemia. We observed dose- and exposure time-dependent immunoprotective effects of IPL CpG-ODN in chicks. We found that IPL delivery of CpG-ODN can induce protective immunity as early as 6 hr that remains effective at least until day 5 post-treatment. Moreover, there were no adverse effects of IPL delivery of CpG-ODN on growth or mortality up to 42 days of age. Based on these findings, it can be suggested that CpG-ODN delivery by IPL route can be a promising alternative to antibiotics for inducing protective immunity in chicks during the critical first week of neonatal life.

Synthetic CpG-ODN rapidly enriches immune compartments in neonatal chicks to induce protective immunity against bacterial infections

Oligodeoxynucleotides containing CpG motifs (CpG-ODN) induce innate immunity against bacterial infections. Despite recent advances, how CpG-ODN alone protects against bacterial infections remained elusive. Here, we report for the first time, to our knowledge, that CpG-ODN orchestrates anti-microbial protective immunity by inducing a rapid enrichment of various immune compartments in chickens. In this study, eighteen-day-old embryonated eggs were injected with either 50 µg of CpG-ODN or saline (~n = 90 per group). In the first experiment, four days after CpG-ODN treatment, chicks were challenged subcutaneously with a virulent strain of Escherichia coli (E. coli) and mortality was monitored for 8 days. We found significant protection, and reduced clinical scores in CpG-ODN treated chicks. To gain insights into mechanisms of protection induced by CpG-ODN, first we investigated cytokine expression kinetics elicited by CpG-ODN. The spleen and lung were collected from embryos or chicks (n = 3-4 per group) at 10 time points post-CpG-ODN inoculation. Multiplex gene analysis (interleukin (IL)-1, IL-4, IL-6, IL-10, IL-18, interferon (IFN)-γ, IFN-α, and lipopolysaccharide induced tumor necrosis factor (LITAF), revealed a significantly higher expression of pro-inflammatory cytokines following CpG-ODN treatment compared to the saline controls. In our study, LITAF stands out in the cytokine profiles of spleen and lungs, underscoring its role in CpG-ODN-induced protection. The third experiment was designed to examine the effects of CpG-ODN on immune cell populations in spleen, lungs, and thymus. Flow cytometry analysis was conducted at 24, 48 and 72 hrs (thymus only collected at 72 hr) after CpG-ODN administration to examine the changes in CD4⁺ and CD8⁺ T-cell subsets, monocyte/macrophage cell populations and their expression of maturation markers (CD40 and CD86). Flow cytometry data indicated a significant enrichment of macrophages, CD4⁺ and CD8⁺ T-cell subsets in both spleen and lungs of CpG-ODN treated embryos and chicks. Macrophages in spleen and lungs showed an upregulation of CD40 but not CD86, whereas thymocytes revealed significantly high CD4 and CD8 expression. Overall, the present study has demonstrated that CpG-ODN provides protection in neonatal chicks against E. coli infection not only by eliciting cytokine responses and stimulating immune cells but also through enriching immunological niches in spleen and lungs.

Theranostics Aspects of Various Nanoparticles in Veterinary Medicine

Nanoscience and nanotechnology shows immense interest in various areas of research and applications, including biotechnology, biomedical sciences, nanomedicine, and veterinary medicine. Studies and application of nanotechnology was explored very extensively in the human medical field and also studies undertaken in rodents extensively, still either studies or applications in veterinary medicine is not up to the level when compared to applications to human beings. The application in veterinary medicine and animal production is still relatively innovative. Recently, in the era of health care technologies, Veterinary Medicine also entered into a new phase and incredible transformations. Nanotechnology has tremendous and potential influence not only the way we live, but also on the way that we practice veterinary medicine and increase the safety of domestic animals, production, and income to the farmers through use of nanomaterials. The current status and advancements of nanotechnology is being used to enhance the animal growth promotion, and production. To achieve these, nanoparticles are used as alternative antimicrobial agents to overcome the usage alarming rate of antibiotics, detection of pathogenic bacteria, and also nanoparticles being used as drug delivery agents as new drug and vaccine candidates with improved characteristics and performance, diagnostic, therapeutic, feed additive, nutrient delivery, biocidal agents, reproductive aids, and finally to increase the quality of food using various kinds of functionalized nanoparticles, such as liposomes, polymeric nanoparticles, dendrimers, micellar nanoparticles, and metal nanoparticles. It seems that nanotechnology is ideal for veterinary applications in terms of cost and the availability of resources. The main focus of this review is describes some of the important current and future principal aspects of involvement of nanotechnology in Veterinary Medicine. However, we are not intended to cover the entire scenario of Veterinary Medicine, despite this review is to provide a glimpse at potential important targets of nanotechnology in the field of Veterinary Medicine. Considering the strong potential of the interaction between the nanotechnology and Veterinary Medicine, the aim of this review is to provide a concise description of the advances of nanotechnology in Veterinary Medicine, in terms of their potential application of various kinds of nanoparticles, secondly we discussed role of nanomaterials in animal health and production, and finally we discussed conclusion and future perspectives of nanotechnology in veterinary medicine.

Veterinary vaccine nanotechnology: pulmonary and nasal delivery in livestock animals

Veterinary vaccine development has several similarities with human vaccine development to improve the overall health and well-being of species. However, veterinary goals lean more toward feasible large-scale administration methods and low cost to high benefit immunization. Since the respiratory mucosa is easily accessible and most infectious agents begin their infection cycle at the mucosa, immunization through the respiratory route has been a highly attractive vaccine delivery strategy against infectious diseases. Additionally, vaccines administered via the respiratory mucosa could lower costs by removing the need of trained medical personnel, and lowering doses yet achieving similar or increased immune stimulation. The respiratory route often brings challenges in antigen delivery efficiency with enough potency to induce immunity. Nanoparticle (NP) technology has been shown to enhance immune activation by producing higher antibody titers and protection. Although specific mechanisms between NPs and biological membranes are still under investigation, physical parameters such as particle size and shape, as well as biological tissue distribution including mucociliary clearance influence the protection and delivery of antigens to the site of action and uptake by target cells. For respiratory delivery, various biomaterials such as mucoadhesive polymers, lipids, and polysaccharides have shown enhanced antibody production or protection in comparison to antigen alone. This review presents promising NPs administered via the nasal or pulmonary routes for veterinary applications specifically focusing on livestock animals including poultry.

Hatchery Vaccination Against Poultry Viral Diseases: Potential Mechanisms and Limitations

Commercial broiler and layer chickens are heavily vaccinated against economically important viral diseases with a view of preventing morbidity, mortality, and production impacts encountered during short production cycles. Hatchery vaccination is performed through in ovo embryo vaccination prehatch or spray and subcutaneous vaccinations performed at the day of hatch before the day-old chickens are being placed in barns with potentially contaminated environments. Commercially, multiple vaccines (e.g., live, live attenuated, and viral vectored vaccines) are available to administer through these routes within a short period (embryo day 18 prehatch to day 1 posthatch). Although the ability to mount immune response, especially the adaptive immune response, is not optimal around the hatch, it is possible that the efficacy of these vaccines depends partly on innate host responses elicited in response to replicating vaccine viruses. This review focuses on the current knowledge of hatchery vaccination in poultry and potential mechanisms of hatchery vaccine-mediated protective responses and limitations.

Induction of a balanced Th1/Th2 immune responses by co-delivery of PLGA/ovalbumin nanospheres and CpG ODNs/PEI-SWCNT nanoparticles as TLR9 agonist in BALB/c mice

To develop effective and safe vaccines with reduced dose of antigen and adjuvant, intelligent delivery systems are required. Many delivery systems have been developed to enhance the biological activity of cytosine-phosphorothioate-guanine oligodeoxynucleotides (CpG ODN) as both immunotherapeutic agents and vaccine adjuvants. In this study we designed a novel CpG ODN delivery system based on single-walled carbon nanotube (SWCNT) functionalized with polyethylenimine (PEI) and alkylcarboxylated PEI (AL-PEI). The physicochemical characteristics, cytotoxicity and cellular uptake studies of these carriers were performed. All carriers were conjugated with CpG ODN followed by co-delivery with ovalbumin (OVA) encapsulated into poly (lactic-co-glycolic acid) nanospheres (PLGA NSs) to enhance the induction of immune responses. The effect of these formulations on antibody (IgG1, IgG2a) and cytokine (IL-1β, IFN-γ, IL-4) production was evaluated in an in vivo experiment. The results showed that all nano-adjuvant formulations had a strong influence in up-regulation of IFN-γ and IL-4 in parallel with high IgG1-IgG2a isotype antibody titers in mice. In particular, SWCNT-AL-PEI nano-adjuvant formulation generated a balanced Th1 and Th2 immune response with more biased toward Th1 response without exhibiting any inflammatory and toxic effects. Therefore this nano-adjuvant formulation could be used as an efficient prophylactic immune responses agent.

Circulating strains of variant infectious bursal disease virus may pose a challenge for antibiotic-free chicken farming in Canada

Antibiotic-free and safe animal products are most desirable among consumers. However, ensuring safe poultry products is a challenging task when the chicken immune system is compromised. Infectious bursal disease virus (IBDV) causes immunosuppression and predisposes chickens to secondary infections. Breeder vaccination against IBDV is routinely practiced for producing chicks with maternally-derived antibody (MAb) to prevent infection in newly hatched chicks. The majority of IBDV circulating in Canadian farms are variant strains (vIBDV). Whether circulating vIBDV strains are immunosuppressive in chicks or are amenable to current vaccine regimens has not previously been tested through challenge studies. In this study, one-day-old broiler chicks (n=240) carrying MAb were obtained from broiler breeders vaccinated with commercial IBDV vaccines. In the first set of experiments (n=40/group), at six days post-hatch, one group was challenged with a Canadian field isolate, vIBDV (strain-SK09) (3×10(3) EID50). The second and the third groups (controls) were inoculated with non-immunosuppressive IBDV D-78 (10×10(3) TCID50) and saline, respectively. Histopathological examination on days 14 and 30 post-challenge revealed that despite the high level of MAb, vIBDV (SK09) caused severe bursal damage in chicks. Another set of experiments with treatment groups as above, demonstrated that pre-exposure of chicks with vIBDV (SK09) caused immunosuppression resulting in significantly higher mortality and disease severity in chicks challenged with a virulent strain of Escherichia coli (E. coli). Our data provide evidence that IBDV strains circulating in Canada are immunosuppressive, not amenable to current anti-IBDV vaccination strategy, and a potential threat to antibiotic-free chicken farming.